Ellipsograph



(No Model.)

A. W. BRADLEY, Jr.

ELLIPSOGRAPH. No. 465,689. Patented'Deo. 22, 1891.

FIG-.1. FIG-.2. I'IQQB. Q FIG-.4

UNITED STATES PATENT ()FFICE.

ARTHUR BRADLEY, J R., OF NElVPORT, KENTUCKY.

ELLIPSOGRAPH.

SPECIFICATION forming part of Letters Patent No. 465,689, dated December 22, 1891. Application filed August 29, 1891- Serial No. 404,083. (No model.)

To all whom it may concern.-

Be it known that I, ARTHUR W. BRADLEY, J r., a citizen of the United States, residing at Newport, in the county of Campbell and State ofKentucky, have invented certain new and useful Improvements in Ellipsographs; and I do hereby declare the following to be a full, clear, and exact description of the invention, reference being had to the annexed drawings, which form part of this specification.

My invention comprises a very simple instrument capable of being readily adjusted to describe ellipses of any desired width and length, the principal members thereof being a pair of legs jointed together in practically the same manner as ordinarydividers or compasses. One of these legs is free to vibrate laterally or in a plane parallel to the major axis of the desired ellipse, but must be incapable of revolving or turning in any direction, and said leg carries an adjustable directrix,which latter consists of a semi-disk that can be shifted longitudinally of the leg and set at different angles. The fellow leg of the instrument is so jointed and coupled to the upper portion of the main leg as to be readily turned around either to the right or left, and has applied to its lower end a pen or pencil or other tracer. Furthermore, a spring is applied to the instrument for the purposeof keeping the inner edge of this turning leg normally in contact with the edge of the directrix or semi-disk while an ellipse is being drawn or described, as hereinafter more fully set forth.

In the annexed drawings, Figurel is an elevation of an instrument embodying my invention, a pencil-point being applied to the turning leg and the latter being in a position for describing one side of an ellipse. Fig. 2 is an enlarged vertical section of the joint and couplings that unite the two legs of the instrument. Fig. 3 is an elevation showing a pen applied to the instrument and the turning leg in position for describing one end of an ellipse. Fig. 4 is an enlarged horizontal section of the coupling of the instrument. Fig. 5 is an enlarged plan of the directrix, the main leg, to which it is applied, being sectioned. Fig. 6 is a side elevation of said directrix. Fig. 7 is an end elevation of the foot,

within which the supporting-leg of the instrument has its bearing. Fig. Sis a verticalsection taken longitudinally of said foot. Fig. 9 is a diagram showing the method of using my instrument.

The main leg A, which is preferably square or non-circular in transverse section, isbeveled off at its lower end, as seen at a in Fig. 8, to fit snugly within a socket Z) of a foot or other bearing B, which foot has three needlepoints 0 C G, of which points the central one C is in line with said beveled end a, while the other points 0 and O" are arranged longitudinally of the foot B and in line with said central point C. The socket b flares in two opposite directions to enable the leg A to vibrate longitudinally of said foot; but any movement of said leg transversely or laterally of the foot is carefully guarded against by slotting the leg and passing a curved bar D through said slot, the bar being held in place by screws cl cl. Bar D is concentric with the extreme point of vibration of the leg A, and this point is located as near the lower edge of foot B as the thickness of the metal will permit.

The upper end of leg A has a lateral projection E, provided with a transverse cylindrical bore 6, to admit the shank or spindle f of a'handle F of the instrument,the fixed end of a plate-spring G being secured to this shank between the projection E and handle F bya pin g or otherwise. Furthermore, this shank carries a transverse pin II, adapted to come in contact with a fixed stop 7L, and thereby prevent the handle F being turned more than half-Way around in either direction, said stop it being secured to the leg A or its projection E. Jointed at f to the lower end of shank f is the turning leg I of the instrument, which legmay be of any shape transversely, provided its inner or effective edge is leveled off, as at i, to afford but a very limited bearing against the directrix. (See Fig. The lower end of this turning leg does not quite reach the surface the foot B rests upon, as the exact point where said leg should touch said surface must be occupied by a pen or pencil or other tracer. In Fig. 1 this point is at the end of a pencil J, the holder of which K has a sleeve and clampscrew 76, said sleeve being traversed by a curved limb i of the leg I. This limb is concentric with the end or point of pencil J in order that said pencil may be arranged to stand about vertical, no matter how widely the instrument may be opened. This point J, the sharp edge e' of the leg, and the pivot or joint f must all be contained in one and the same plane, and the free end of spring G must so bear against said leg I as to force it toward the other leg A, in order that this turning leg I may normally be in contact with the sharp edge lot the directrix L, previously alluded to. Said directrix is usually a semidisk, and is hinged at m to a square sleeve M, adapted to be adjusted along the main leg A and to be held at any desired point by a clamp-screw N.

O is a segment-gear secured to the directrix L and concentric with its pivot 7%, said gear being operated by an endless screw P, having a turning knob or handle 19, and the screw being carried by a bearing projecting from the side of sleeve M.

R in Fig. 3 is a drawing-pen attached to the curved limb t" of the leg I.

S is a sheet of paper or other surface upon which an ellipse is to be described.

To illustrate the method of using my instrument, let it be supposed that the dotted line U in Fig. 9 represents the major axis of the desired ellipse and the dotted line V one half of the minor axis of the same, said lines being first drawn upon a sheet of paper or other surface. The instrument is then placed .upon this surface so as to locate the central point C of the footB at the exact place where the lines U V intersect; or, in other words, at the center of the figure, the other points 0 0 being disposed along the major axis U, the small holes made in the paper by these various points being indicated by the dots 0 0'0. Olamp-screwN is then loosened, so as to leave the directrixL free, and springG is compressed for the purpose of permitting a ready setting of the leg I, which is turned around until the pen R or pencil J just touches one end of the major axis-say at the point uthe main leg A being vibrated on its bearing a to enable the instrument to span this distance. (See Fig. 3.) Sleeve M is now slid up the main leg A until the sharp edge t' of turning leg I bears against the margin of disk L at or near the axis of the latter, and then this sleeve is clamped to said leg A by the screw N. The

leg I, being still free from the stress of spring G, is swung around and drawn inward until the pen or pencil reaches the point 1; at the end of the minor axis V, at which moment the screw P is turned, so as to elevate or depress the directrix L, and thereby bring its edge in contact with the sharp edge 2' of leg I. (See Fig. 1.) Said leg is again turned back until the pencil or pen once more reaches the point a, and spring G is allowed to expand and exert its full force against the upper end of the leg, thereby holding the latter against the edge of the directrix L. Handle F is now grasped for the purpose of operating the instrument in the same manner as a compass; but as the leg A cannot turn the leg I is the only one thus set in motion. Consequently the turning of said handle causes said leg to swing around the directrix L, thereby describing the-semi-ellipse u o u. The

instrument is then raised from oif the paper,

be made longer or shorter a new adjustment of the parts will be necessary. In case there is a very material difference between the length of the major and minor axis of the ellipse it may be necessary to change the inclination of the pen or pencil after describing a portion of the figure; but such an inclination will not destroy the symmetry or regularity of the figure, because the limb '11 of the leg is concentric with the point of the tracer.

In constructing this instrument care must be taken to have the points 0 O C, directrixaxis m, and leg-joint f all lie in one and the same plane.

The dotted lines T in Fig. 1 indicate an india-rubber band or other pulling-spring capable of drawing the leg I toward the leg A, thereby indicating that the invention is not limited to the exact construction previously described. In another modification a semi-elliptic directrix may take the place of the half-disk L.

I claim as my invention- 1. The combination,.in an ellipsograph, of a vibrating but non-rotatable leg, an adj ustable directrix applied thereto, a turning legpivoted near the upper end of the instrument, a tracer applied near the lower end of said turning leg, and a spring that normally holds the latter against said directrix, substantially as herein described.

2. The combination, in an ellipsograph of the class specified, of the sliding sleeve M, having a clamp-screw N, a directrix L, hinged to said sleeve at m and having a segmentgear 0, and an endless screw P, carried by said sleeve and engaging with said gear 0,

for the purpose described.

3. The combination, in an ellipsograph of the class specified, of the foot B, having a concave recess 1), a curved bar D, and three points 0 C 0, arranged longitudinally of said foot and in line with each other, and a non-rotatable leg A, having a beveledpoint a, that bears in the center of said recess, said bar D being concentric with this point a, for the purpose described.

4. The combination, in an ellipsograph of the class specified, of the turning leg I, having a curved limb t" concentric with the tracer applied to the lower end of said leg, as described.

5. The combination, in an ellipsograph of the class specified, of a turning leg jointed to a shank of the instrument-handle, a projection from said shank, and a fixed stop that prevents said handle being turned more than half-way in either direction, for the purpose described.

6. The combination, in an ellipsograph ot the class specified, of a leg jointed to the shank of a turning handle and a spring having one end secured to said shank and its free endiin contact with saidlegfor the purpose of forcing the latter inwardly, as herein described.

7. An ellipsograph consisting of a vibrating but non-rotatable leg A, an adjustable direcpresence of two witnesses.

ARTHUR IV. BRADLEY, JR.

Witnesses:

JAMES H. LAYMAN, A. B. DUNLAP. 

